1. Field of Invention
The present invention relates to an endovascular stent and, more specifically, to a endovascular stent having a cephalic section with a cross-sectional area, a caudal section with a cross-sectional area that is smaller than the cephalic section cross-sectional area, and a tapered mid-section disposed therebetween. Methods of utilizing the stent to treat abdominal aortic aneurysms and distal iliac aneurysms are also provided.
2. Background Information
There have been numerous patents upon stents and endovascular stent grafts. When a person develops abdominal aortic aneurysm, there is a high risk of rupture. Treatment options include surgery or endovascular stent graft placement.
One of the limitations of stent graft placement has been the size of the abdominal aorta at the level of the neck or the region just distal to the renal arteries. Typically, the stent is limited to a 28 mm diameter and must be placed in a portion of the abdominal aorta having a similar diameter. There is one product currently available to accommodate larger aortas, but you need an expanded inventory to accommodate stents having the larger sizes. A second problem with larger stent diameters is the delivery device needed to advance the system. In order to advance most stent systems, you will need at least 7-8 mm diameter of the iliac arteries.
This invention provides the means for treating abdominal aortic aneurysms with standard modular endovascular stent graft systems. The invention is a tapered stent graft system that allows it to be joined with a secondary, standard modular endovascular stent graft system. The cephalic end, towards the patient""s head, includes a cephalic section forming a cephalic plenum. The cephalic section has a cross-sectional area. The caudal end, towards the patient""s feet, includes a caudal section forming a caudal plenum. The caudal section has a smaller cross-sectional area than the cephalic section. Between the cephalic section and the caudal section is a tapered mid-section.
The endovascular stent is composed of self expanding stent material to provide constant expansion of the cuff against the aortic wall and the adjoining stent graft system. The graft material attached to the stent will be compatible with endovascular graft material used in arterial treatment.
On the cephalic end, there are a plurality of struts that are not covered with graft material. The remaining portion, or approximately ⅘, of the endovascular stent is covered with a graft material attached to the underlying stent. The purpose of the exposed or uncovered cephalic end is to allow possible expansion of the system against the aorta and cross important origins, such as the renal arteries. This provides the necessary anchor for the extension cuff. It will be capable of expanding up to a diameter of 35 mm or higher if needed.
At the caudal end of the endovascular stent, the diameter of the endovascular stent decreases significantly. The area of the covered stent between the larger cephalic and narrower caudal is a smooth but quick transition or taper. The narrow caudal end will extend a certain distance to allow other modular stent graft systems to be attached. The narrow caudal end may have a flare or bell-bottom end to facilitate re-canalization.
At the tips and mid section of the endovascular stent will be a radiopaque markers to help visualize the cephalic and caudal ends under fluoroscopy.
It is an object of this invention to provide an endovascular stent which includes a generally cylindrical cephalic section defining a cephalic lumen and having a cross-sectional area, a tapered mid-section, caudal section defining a caudal lumen and having a cross-sectional area, the mid-section disposed between, and attached to both the cephalic section and the caudal section, and wherein the cephalic cross-sectional area is larger than the caudal cross-sectional area and the mid-section tapers from the cephalic cross-sectional area to the caudal cross-sectional area.
It is a further object of this invention to provide a method of using a endovascular stent having a different sized cylindrical end sections and a tapered section therebetween for treating an abdominal aortic aneurysm, wherein the method includes the steps of: providing a collapsible endovascular, collapsing the endovascular stent into a collapsed configuration; inserting the endovascular stent into a patient via a vascular sheath to a location within the abdominal aorta adjacent a abdominal aortic aneurysm, expanding the endovascular stent to an expanded configuration wherein the cephalic section engages the abdominal aorta and the caudal section extends into the abdominal aortic aneurysm.
It is a further object of this invention to provide a method of using a endovascular stent having a different sized cylindrical end sections and a tapered section therebetween for treating a distal iliac aneurysm, wherein the method includes the steps of: providing a collapsible endovascular, inserting the endovascular stent into a patient via a vascular sheath to a location within an iliac artery adjacent to a iliac aneurysm and expanding the endovascular stent to an expanded configuration wherein the flared section engages the iliac artery.